3 results
Mikolaj Bojanczyk ; Luc Segoufin.
We study tree languages that can be defined in \Delta_2 . These are tree languages definable by a first-order formula whose quantifier prefix is forall exists, and simultaneously by a first-order formula whose quantifier prefix is . For the quantifier free part we consider two signatures, either the […]
Published on October 20, 2010
Mikołaj Bojańczyk ; Michał Pilipczuk.
The classic algorithm of Bodlaender and Kloks [J. Algorithms, 1996] solves the following problem in linear fixed-parameter time: given a tree decomposition of a graph of (possibly suboptimal) width k, compute an optimum-width tree decomposition of the graph. In this work, we prove that this problem […]
Published on February 3, 2022
Mikołaj Bojańczyk ; Bartek Klin ; Sławomir Lasota.
We study languages over infinite alphabets equipped with some structure that can be tested by recognizing automata. We develop a framework for studying such alphabets and the ensuing automata theory, where the key role is played by an automorphism group of the alphabet. In the process, we generalize […]
Published on August 15, 2014